BIO SCI 47 Chapter Notes - Chapter 7: Gonadotropin-Releasing Hormone, Erectile Dysfunction, Enkephalin
29 Apr 2018
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Sex and Reproduction
Males: Testosterone and Loss of Erections
● Hypothalamus releases LHRH
○ Stimulates pituitary to release LH and FSH
● LH stimulates testes to release testosterone
● FSH stimulates sperm production
● When stressed system is inhibited
○ LHRH concentrations decline
○ Then LH and FSH decline
○ Testes shut down
○ Decline in circulating testosterone levels
● Human societies with less stress have lower testosterone levels
○ Lower ranking people have less testosterone
● When stressed, endorphins and enkephalins block LHRH receptors
● With the onset of stress, LHRH secretion declines
○ Prolactin decreases pituitary’s sensitivity to LHRH
● Glucocorticoids block response of testes to LH
● Erections are accomplished by activating parasympathetic system, must be calm
● Sex brings you back to the sympathetic (the four Fs)
○ Ejaculation is when parasympathetic gives up
● If you’re stressed it is hard to be in the parasympathetic, so it is hard to get an erection
● If you already have the erection and then get stressed, you prematurely ejaculate
● Erectile dysfunction is a stressor
● In a lot of species, stressors associated with mating season competition or with
mating itself not only don't suppress the reproductive system, but can stimulate it
a bit
○ Stressor doesn't cause secretion of stress hormones; in other cases, the
stress hormones are secreted but the reproductive system becomes
insensitive to them
Our Friend the Hyena
● Among hyenas, females are sexually dominant
Document Summary
Stimulates pituitary to release lh and fsh. Human societies with less stress have lower testosterone levels. When stressed, endorphins and enkephalins block lhrh receptors. With the onset of stress, lhrh secretion declines. Glucocorticoids block response of testes to lh. Erections are accomplished by activating parasympathetic system, must be calm. Sex brings you back to the sympathetic (the four fs) If you"re stressed it is hard to be in the parasympathetic, so it is hard to get an erection. If you already have the erection and then get stressed, you prematurely ejaculate. In a lot of species, stressors associated with mating season competition or with mating itself not only don"t suppress the reproductive system, but can stimulate it a bit. Stressor doesn"t cause secretion of stress hormones; in other cases, the stress hormones are secreted but the reproductive system becomes insensitive to them. Looks like hyenas possess machinery of both sexes. Female has fake scrotal sac made of compacted fat cells.
